The goal of this project is a computer-simulation program that allows efficient reversed-phase HPLC method development by simultaneously varying temperature and either solvent strength (%B) or gradient steepness b. Phase-I achieved the following objectives: (1) an algorithm was developed that allows such optimizations to be carried out with only 4 experimental runs over the usual temperature range (ambient to 70 degrees centigrade): (2) sufficient samples were examined to conclude that this scheme will be effective for many (maybe most) samples; (3) rules for predicting which samples are less likely to be separated in this way were developed; (4) the choice of other conditions (pH, column type) that enhance temperature and solvent-strength selectivity was investigated and preliminary recommendations were made: (5) preliminary computer-simulation software was created. Phase II proposes: (1) expanding and improving the computer program started in Phase I: (2) enhancing the software for more efficient and reliable use of experimental runs, including improved peak tracking; (3) automating the selection of optimum final gradients, including attention to method ruggedness; (4) extending this approach for use in optimizing solvent type (methanol/acetonitrile mixtures) and other variables, and (5) incorporating additional features for the practical application of HPLC computer simulation. PROPOSED COMMERCIAL APPLICATION Upon Phase III commercialization, the proposed program will be available for use in any HPLC laboratory as an aid for method development. This will result in (1) better analytical separations and (2) lower costs to both develop and carry out these separations. The proposed software will also encourage the development and use of more robust and easily transferable gradient methods. For these reasons, sales of our simulation software should increase substantially.